Prime Minister Junichiro Koizumi underwent endoscopic surgery Wednesday after doctors found a polyp in his colon during a regular health checkup, the prime minister's office announced.

The removal of the 2-cm benign growth went "safely and perfectly," and there was no recognizable bleeding, the office quoted doctors as saying.

"It's not a big deal," Chief Cabinet Secretary Yasuo Fukuda told a regularly scheduled news conference in the afternoon. "The prime minister will work as usual from tomorrow."

Koizumi's health checkup at the International Medical Center of Japan in Shinjuku Ward, Tokyo, is the second he has undergone this year. His last visit was Aug. 13.

News that he was returning to the hospital fired speculation that something irregular had been found during his first checkup.

Fukuda said he had no idea whether the polyp was found in August. Koizumi has never complained about his health condition, he said.

"I don't know in detail, but he went through the checkup this time, (the polyp) was found, and he had it removed -- it's as simple as that," Fukuda said, trying to play down the potential impact of the news as Koizumi prepares for the Sept. 20 Liberal Democratic Party presidential election.

Koizumi checked into the medical center at 7:30 a.m. and left shortly before 4 p.m., the prime minister's office said.

Asked as he left the center if he was OK for the presidential race, Koizumi replied, "Fine, thank you."